High-flux Inverse Compton Scattering for Medical, Industrial and Security

Applications

Applications of ICS

• Medical Imaging

• Radiotherapy

• Non-Destructive Testing

• Research

• Security/Defense: long-range detection of special nuclear materials via photofission

• > 6 MeV monochromatic X-ray source with low divergence

• Recently completed a Phase I SBIR for DTRA

• All applications require more average flux than currently produced...

• 1012 photons/second required

Our approach

• Use proven technology (photoinjector, ultra-fast laser)

• Increase “effective” repetition rate using laser pulse recirculation, multiple electron bunches

• Goal: X 100 increase in flux

• Use Adaptive Optics/Feedback system for laser and accelerator to increase stability

• Integrate laser recirculator/final focus and electron beam final focus system (PMQs) into a single vacuum box

• Eventually implement high-rep rate gun (1 kHz) and laser to gain another factor of 100 in flux

• 100 - 10,000 improvement in average flux

Laser recirculator

• Recirculation Injection by Nonlinear Gating (RING)

• Developed at LLNL [I. Jovanovic et al]

• IR pulse injected and frequency-doubled

• Green pulse recirculated through final focus

• Advantage: simple, inexpensive, can handle high power

• Disadvantage: “Ring-down”

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Adaptive Optics/Feedback

• Laser AO system before Interaction Region

• Beam stabilizer: fast steering mirrors and position sensitive detectors

• Wavefront corrector: deformable mirror and Shack-Hartmann sensor

• Accelerator diagnostics feedback to control system

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Interaction Box

• Integrated RING and electron beam final focus

• Adjustable Halbach-PMQ triplet

• IP diagnostic for alignment of beams

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High-Rep Rate Photoinjector

• Ongoing development at RadiaBeam (not part of this proposal)

• High-gradient (> 100 MV/m), 1 kHz photoinjector

• Novel fabrication technique for copper RF structures allows better cooling

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Proof-of-Concept Experiment

• Currently awaiting Phase II funding from DTRA

• RING, PMQ system, interaction box, AO system, diagnostics, will be fabricated, tested at RadiaBeam, and installed at ATF

• ATF Nd:YAG laser will be upgraded

• Additional amplifier stage for interaction pulse

• Reconfigured to produce bunch train for gun

• Experiment will be performed

• First optimize electron and laser beam transport to IP

• Then install components, perform single-bunch ICS

• Finally, attempt multi-bunch ICS

Parameters

Schedule